Word Problem

Question

A family has two cars. The first car has a fuel efficiency of 35 miles per gallon of gas and the second has a fuel efficiency of 30 miles per gallon of gas. During one particular week, the two cars went a combined total of 1750 miles, for a total gas consumption of 55 gallons. How many gallons were consumed by each of the two cars that week?

Answer 1

Kathy, if car 1 used g gallons, then car 2 used 55 - g gallons, right?

 

Since mpg is found by dividing the total miles by the gallons used, then the total miles is the mpg x the gallons used.

 

For example, 5000 miles on 250 gallons is 5000 /250 = 20 mpg, but 20 mpg x 250 gallons = 5000 miles, right?

 

Soooooo, car 1 drove 35g miles and car 2 drove 30(55 - g) miles, for a total of 1750 miles.

 

35g + 30(55 - g) = 1750

35g + 1650 - 30g = 1750

                          5g = 100

                             g = 20

 

Car 1 used 20 gallons, and car 2 used 55 - 20 = 35 gallons.

 

Hope this helps!

 

35g + 1650 - 30g =